A graded semantics for counterfactuals

This article presents an extension of Lewis’ analysis of counterfactuals to a graded framework. Unlike standard graded approaches, which use the probabilistic framework, we employ that of many-valued logics. Our principal goal is to provide an adequate analysis of the main background notion of Lewis’ approach—the one of the similarity of possible worlds. We discuss the requirements imposed on the analysis of counterfactuals by the imprecise character of similarity and concentrate in particular on robustness, i.e., the requirement that small changes in the similarity relation should not significantly change the truth value of the counterfactual in question. Our second motivation is related to the logical analysis of natural language: analyzing counterfactuals in the framework of many-valued logics allows us to extend the analysis to counterfactuals that include vague statements. Unlike previous proposals of this kind in the literature, our approach makes it possible to apply gradedness at various levels of the analysis and hence provide a more detailed account of the phenomenon of vagueness in the context of counterfactuals. Finally, our framework admits a novel way of avoiding the Limit Assumption, keeping the core of Lewis’ truth condition for counterfactuals unchanged.

     

Counterfactuals and Historical Possibility

We show that truth conditions for counterfactuals need not always be given in terms of a vague notion of similarity. To this end, we single out the important class of historical counterfactuals and give formally rigorous truth conditions for these counterfactuals, employing a partial ordering relation called “comparative closeness” that is defined in the framework of branching space-times. Among other applications, we provide a detailed analysis of counterfactuals uttered in the context of lost bets. In an appendix we compare our theory with the branching space-times based reading of counterfactuals recently proposed by Belnap.     

Interventionist counterfactuals

A number of recent authors (Galles and Pearl, Found Sci 3 (1):151?C182, 1998; Hiddleston, No?s 39 (4):232?C257, 2005; Halpern, J Artif Intell Res 12:317?C337, 2000) advocate a causal modeling semantics for counterfactuals. But the precise logical significance of the causal modeling semantics remains murky. Particularly important, yet particularly under-explored, is its relationship to the similarity-based semantics for counterfactuals developed by Lewis (Counterfactuals. Harvard University Press, 1973b). The causal modeling semantics is both an account of the truth conditions of counterfactuals, and an account of which inferences involving counterfactuals are valid. As an account of truth conditions, it is incomplete. While Lewis??s similarity semantics lets us evaluate counterfactuals with arbitrarily complex antecedents and consequents, the causal modeling semantics makes it hard to ascertain the truth conditions of all but a highly restricted class of counterfactuals. I explain how to extend the causal modeling language to encompass a wider range of sentences, and provide a sound and complete axiomatization for the extended language. Extending the truth conditions for counterfactuals has serious consequences concerning valid inference. The extended language is unlike any logic of Lewis??s: modus ponens is invalid, and classical logical equivalents cannot be freely substituted in the antecedents of conditionals.     

Counterfactuals and Spatiotemporal Events

One of the basic assumptions of David Lewis's formal semantics of counterfactuals is that the crucial relation of comparative similarity between possible worlds is a linear ordering.Yet there are arguments that when we take into account relativistic features of space-time, this relationshould be only a partial ordering. The first part of the paper deals with the question of how to formulate appropriatetruth conditions for counterfactuals under the supposition of a partial ordering of possible worlds. Such truthconditions will be put forward, and it will be argued that they are more general than those proposed in recentliterature, because they turn out to be applicable also when the so-called Limit Assumption is not met. The secondpart analyzes two relativistically invariant ways of interpreting spatiotemporal counterfactuals with antecedentsreferring to free-chance point events. After briefly examining key differences between these two approaches,the issue of their extension for a broader class of antecedents will be addressed. Following the approach of Finkelstein (1999), who has proposed a specifically designed similarity relation between possible worlds, servingas a generalization tool in the case of one of the above intuitions, the possibility of a similar extension forthe second interpretation will be considered. The main result of the paper is the theorem to the effect that thegeneralization of the second intuition is impossible to obtain. More specifically, the theorem proved in the paperstates that there is no similarity relation which together with the Lewis-style truth conditions for counterfactualswould imply the second of the above interpretations as a special case. Some consequences of thistheorem for the applicability of the Lewis logic of counterfactuals to quantum phenomena will be briefly mentionedat the end of the paper.     

Probabilities of counterfactuals and counterfactual probabilities

Probabilities figure centrally in much of the literature on the semantics of conditionals. I find this surprising: it accords a special status to conditionals that other parts of language apparently do not share. I critically discuss two notable ‘probabilities first’ accounts of counterfactuals, due to Edgington and Leitgeb. According to Edgington, counterfactuals lack truth values but have probabilities. I argue that this combination gives rise to a number of problems. According to Leitgeb, counterfactuals have truth conditions-roughly, a counterfactual is true when the corresponding conditional chance is sufficiently high. I argue that problems arise from the disparity between truth and high chance, between approximate truth and high chance, and from counterfactuals for which the corresponding conditional chances are undefined. However, Edgington, Leitgeb and I can unite in opposition to Stalnaker and Lewis-style ‘similarity’ accounts of counterfactuals.     

COUNTERFACTUALS WITH TRUE COMPONENTS

One criticism of David Lewis's account of counterfactuals is that it sometimes assigns the wrong truth-value to a counterfactual when both antecedent and consequent happen to be true. Lewis has suggested a possible remedy to this situation, but commentators have found this to be unsatisfactory. I suggest an alternative solution which involves a modification of Lewis's truth conditions, but which confines itself to the resources already present in his account. This modification involves the device of embedding one counterfactual within another. On the revised set of truth conditions, counterfactuals with true components are sometimes true and sometimes false, in a way that is more in keeping with our intuitive judgments about such statements.     

The Problem of Counterfactuals in Substituted Judgement Decision‐Making

The standard by which we apply decision‐making for those unable to do so for themselves is an important practical ethical issue with substantial implications for the treatment and welfare of such individuals. The approach to proxy or surrogate decision‐making based upon substituted judgement is often seen as the ideal standard to aim for but suffers from a need to provide a clear account of how to determine the validity of the proxy's judgements. Proponents have responded to this demand by providing the truth‐conditions for the substituted judgement in terms of counterfactual reasoning using a possible worlds semantics. In this paper, I show how these underpinnings fail to support the substituted judgement approach as a reasonable standard for decision‐making. Firstly, I show how this counterfactual element has been poorly interpreted. I then explain how various accounts have failed to reflect problems and limitations associated with providing an interpretation of their truth‐conditions using counterfactuals. Finally, I argue that, even when we attend to the initial problems of providing a counterfactual analysis, it still deeply problematic as a means of determining the validity of substituted judgements for two main reasons. Firstly, making determinate judgements as to the truth‐value of these judgements will often not be possible and, secondly, there is a strong requirement when interpreting many counterfactual claims to charitably accede to their being true. I conclude that substituted judgements, as interpreted through counterfactual reasoning and possible worlds semantics, do not therefore provide an adequate standard for surrogate decision‐making.     

Thought-experiment intuitions and truth in fiction

What sorts of things are the intuitions generated via thought experiment? Timothy Williamson has responded to naturalistic skeptics by arguing that thought-experiment intuitions are judgments of ordinary counterfactuals. On this view, the intuition is naturalistically innocuous, but it has a contingent content and could be known at best a posteriori. We suggest an alternative to Williamson’s account, according to which we apprehend thought-experiment intuitions through our grasp on truth in fiction. On our view, intuitions like the Gettier intuition are necessarily true and knowable a priori. Our view, like Williamson’s, avoids naturalistic skepticism.     

Analysing Causality: The Opposite of Counterfactual is Factual

Using Jim Woodward's Counterfactual Dependency account as an example, I argue that causal claims about indeterministic systems cannot be satisfactorily analysed as including counterfactual conditionals among their truth conditions because the counterfactuals such accounts must appeal to need not have truth values. Where this happens, counterfactual analyses transform true causal claims into expressions which are not true.     

A Lottery Paradox for Counterfactuals Without Agglomeration

We will present a new lottery‐style paradox on counterfactuals and chance. The upshot will be: combining natural assumptions on (i) the truth values of ordinary counterfactuals, (ii) the conditional chances of possible but non‐actual events, (iii) the manner in which (i) and (ii) relate to each other, and (iv) a fragment of the logic of counterfactuals leads to disaster. In contrast with the usual lottery‐style paradoxes, logical closure under conjunction—that is, in this case, the rule of Agglomeration of (consequents of) counterfactuals—will not play a role in the derivation and will not be entailed by our premises either. We will sketch four obvious but problematic ways out of the dilemma, and we will end up with a new resolution strategy that is non‐obvious but (as we hope) less problematic: contextualism about what counts as a proposition. This proposal will not just save us from the paradox, it will also save each premise in at least some context, and it will be motivated by independent considerations from measure theory and probability theory.     

Possible World Semantics and True‐True Counterfactuals

The standard semantics for counterfactuals ensures that any counterfactual with a true antecedent and true consequent is itself true. There have been many recent attempts to amend the standard semantics to avoid this result. I show that these proposals invalidate a number of further principles of the standard logic of counterfactuals. The case against the automatic truth of counterfactuals with true components does not extend to these further principles, however, so it is not clear that rejecting the latter should be a consequence of rejecting the former. Instead I consider how one might defuse putative counterexamples to the truth of true‐true counterfactuals.     

Grounding Entails Counterpossible Non‐Triviality

This paper outlines a non‐reductive counterfactual account of grounding along interventionist lines, and uses the account to argue that taking grounding seriously requires ascribing non‐trivial truth‐conditions to a range of counterpossible counterfactuals. This result allows for a diagnosis of a route to scepticism about grounding, as deriving at least in part from scepticism about non‐trivial counterpossible truth and falsity.     

Counterfactual structure and learning from experience in negotiations

Reflecting on the past is often a critical ingredient for successful learning. The current research investigated how counterfactual thinking, reflecting on how prior experiences might have been different, motivates effective learning from these previous experiences. Specifically, we explored how the structure of counterfactual reflection - their additive (“If only I had”) versus subtractive (“If only I had not”) nature - influences performance in dyadic-level strategic interactions. Building on the functionalist account of counterfactuals, we found across two experiments that generating additive counterfactuals about a previous negotiation produced an advantage for negotiators over their previous performance compared to subtractive counterfactuals, both in terms of obtaining value for oneself and conceiving creative agreements. Additive counterfactuals enabled negotiators to more effectively extract lessons from past experiences to improve their current negotiation performance.     

Counterfactual Causation and Mental Causation

Counterfactual conditionals have been appealed to in various ways to show how the mind can be causally efficacious. However, it has often been overestimated what the truth of certain counterfactuals actually indicates about causation. The paper first identifies four approaches that seem to commit precisely this mistake. The arguments discussed involve erroneous assumptions about the connection of counterfactual dependence and genuine causation, as well as a disregard of the requisite evaluation conditions of counterfactuals. In a second step, the paper uses the insights of the foregoing analyses to formulate a set of counterfactuals-based conditions that are characterized as sufficient to establish singular causal claims. The paper concludes that there are ample reasons to believe that some mental events satisfy all these conditions with respect to certain further events and, hence, that mental events sometimes are causes.     

带良好条件句的真理不动点理论

各种真理不动点理论的一个主要问题在于：它们通常缺乏像样的条件句。本文旨在提出两种新的想法去处理这个问题。在介绍克里普克的真理不动点理论之后,本文的作者探讨了对真理不动点理论的种种反对意见,并回答了其中的一部分。然后,作者说明了菲尔德的真理理论,并说明该理论如何在克里普克的真理不动点理论至上增加了条件句。不过,本文的作者争论说,菲尔德的条件句仍有许多不尽理想之处。为了弥补这些缺点,作者提出了两个想法：一个是在不动点理论至上增加亚当斯条件句,另一个则是在其上增加史多内克条件句。     

Knowledge,adequacy, and approximate truth

Approximation involves representing things in ways that might be close to the truth but are nevertheless false. Given the widespread reliance on approximations in science and everyday life, here we ask whether it is conceptually possible for false approximations to qualify as knowledge. According to the factivity account, it is impossible to know false approximations, because knowledge requires truth. According to the representational adequacy account, it is possible to know false approximations, if they are close enough to the truth for present purposes. In this paper, we adopt an experimental methodology to begin testing these two theories. When an agent provides a false and practically inadequate answer, both theories predict that people will deny knowledge. But the theories disagree about an agent who provides a false but practically adequate answer: the factivity hypothesis again predicts knowledge denial, whereas the representational adequacy hypothesis predicts knowledge attribution. Across two experiments, our principal finding was that people tended to attribute knowledge for false but practically adequate answers, which supports the representational adequacy account. We propose an interpretation of existing findings that preserves a conceptual link between knowledge and truth. According to this proposal, truth is not necessary for knowledge, but it is a feature of prototypical knowledge.     

What are impossible worlds?

In this paper, I argue for a particular conception of impossible worlds. Possible worlds, as traditionally understood, can be used in the analysis of propositions, the content of belief, the truth of counterfactuals, and so on. Yet possible worlds are not capable of differentiating propositions that are necessarily equivalent, making sense of the beliefs of agents who are not ideally rational, or giving truth values to counterfactuals with necessarily false antecedents. The addition of impossible worlds addresses these issues. The kinds of impossible worlds capable of performing this task are not mysterious sui generis entities, but sets of structured propositions that are themselves constructed out of possible worlds and relations. I also respond to a worry that these impossible worlds are unable to represent claims about the shape of modal space itself.     

An objective counterfactual theory of information

We offer a novel theory of information that differs from traditional accounts in two respects: (i) it explains information in terms of counterfactuals rather than conditional probabilities, and (ii) it does not make essential reference to doxastic states of subjects, and consequently allows for the sort of objective, reductive explanations of various notions in epistemology and philosophy of mind that many have wanted from an account of information.     

Judgment in Fiction

Abstract

In this paper, I show that in order to gain an understanding of the facts about fiction it is more fruitful to pursue an analysis of judgment in fiction than an analysis of truth in fiction. I do so in two steps. First I take the analyses of truth in fiction which David Lewis provides in “Truth in Fiction”, which are formulated in terms of possible worlds, and provide counterpart analyses of judgment in fiction, formulated in terms of (mental) models and rules for the construction of (mental) models. In the course of discussion I identify various problems for Lewis’s account of truth in fiction and solve or dissolve them using the account of judgment in fiction. Second, I show that once we have an analysis of judgment which appeals to rules, we can extend the account of judgment by using Lewis’s account of accommodation and resistance in “Scorekeeping in a Language Game” to explain the evolution of the genres of fiction, construed as systems of rules. The result is to provide a dynamic account of judgment which does justice to modern poststructuralist observations in the philosophy of literature.     

Analyticity and Possible-World Semantics

Standard approaches to possible-world semantics allow us to define necessity and logical truth, but analyticity is considerably more difficult to account for. The source of this difficulty lies in the received model-theoretical conception of a language interpretation. In intuitive terms, analyticity amounts to truth in virtue of meaning alone, i.e. solely in virtue of the interpretation of linguistic expressions. In other words, an analytic sentence should remain true under all variations of ‘extralinguistic reality’ as long as the interpretation is kept constant. However, the received conception of an interpretation as a mapping from language to a model frame hinders keeping the interpretation constant while varying other components of the model. To make room for analyticity, the concept of an interpretation should therefore be revised. The latter should be made richer in content than it has usually been assumed. As a by-product, this revision also gives us a one-dimensional analogue of the influential two-dimensional account of a priori. We are thus able to map out the network of formal connections between the notions of analyticity, apriority, logical truth and necessity.